+**Congress**
+
+OpenStack `Congress`_ is a Governance as a Service (previously Policy as a
+Service). Congress implements Doctor Inspector as it can inspect a fault
+situation and propagate errors onto other entities.
+
+.. _Congress: https://wiki.openstack.org/wiki/Congress
+
+Congress is deployed by OPNFV installers. You need to enable doctor
+datasource driver and set policy rules. By the example configuration below,
+Congress will force down nova compute service when it received a fault event
+of that compute host. Also, Congress will set the state of all VMs running on
+that host from ACTIVE to ERROR state.
+
+.. code-block:: bash
+
+ openstack congress datasource create doctor doctor
+
+ openstack congress policy rule create \
+ --name host_down classification \
+ 'host_down(host) :-
+ doctor:events(hostname=host, type="compute.host.down", status="down")'
+
+ openstack congress policy rule create \
+ --name active_instance_in_host classification \
+ 'active_instance_in_host(vmid, host) :-
+ nova:servers(id=vmid, host_name=host, status="ACTIVE")'
+
+ openstack congress policy rule create \
+ --name host_force_down classification \
+ 'execute[nova:services.force_down(host, "nova-compute", "True")] :-
+ host_down(host)'
+
+ openstack congress policy rule create \
+ --name error_vm_states classification \
+ 'execute[nova:servers.reset_state(vmid, "error")] :-
+ host_down(host),
+ active_instance_in_host(vmid, host)'
+